In recent years, an automobile requires various information such as a load acting on a vehicle wheel or a rotation speed of the vehicle wheel in order to carry out a driving control in a traveling mode. In order to obtain such information, there is proposed a technique in which a sensor is provided in a vehicle-wheel rolling bearing attached with a vehicle wheel of an automobile.
As the known vehicle-wheel rolling bearing, there is a bearing including a cylindrical fixed ring which is fixed to a vehicle body; a rotary ring which is provided in the fixed ring in an inner radial direction so as to attach a vehicle wheel thereto; and plural rows of rolling elements which are provided between the fixed ring and the rotary ring so as to roll. In the bearing, the above-described sensor is provided in the fixed ring, and the information of the rotary ring is obtained from the sensor.
In the bearing, a through hole is formed through the fixed ring in a radial direction, and the sensor is inserted into the through hole. In addition, a measurement portion of the sensor is opposed to the outer peripheral surface of the rotary ring so that the sensor acquires the information of the rotary ring.
However, in the vehicle-wheel rolling bearing, it is necessary to form plural through holes in the fixed ring in order to provide plural sensors in the fixed ring. In this case, another penetration process is required in the manufacture process of the fixed ring, and the through holes are respectively required to be equipped with the sensors, thereby complicating the assembling process. In addition, it is necessary to adjust a gap between the sensor and the rotary ring in every sensor. As a result, a problem arises in that the number of assembling processes increases.